Liked them all, very minor changes in each one. Ncode was slightly softer than the K-Factor, which is the stiffest one of the bunch. BLX was VERY muted, almost too muted for me. Prostaff BLX2 edition is really nice, feels faster than the previous 3 and has more of the K-Factor feel.

The nCode felt muddled, not crsip. The kfactor could not be played without a damp, a little too lively for me and rather stiff. The blx90 was something of a tank, like the k90 but had the soft touch of the ncode90, with a much more clean feel to it.

The PS90 has a little from all three. The easiness in swing of the ncode. The solidity of the k90 and the dampened (just a touch) feel of the blx90.

The nCode felt muddled, not crsip. The kfactor could not be played without a damp, a little too lively for me and rather stiff. The blx90 was something of a tank, like the k90 but had the soft touch of the ncode90, with a much more clean feel to it.

The PS90 has a little from all three. The easiness in swing of the ncode. The solidity of the k90 and the dampened (just a touch) feel of the blx90.

I definitely like this iteration the best of all. Like all tour90s, it just punishes the ball and forces you to anticipate and setup early. But i love the feel on this one, much more so than n,k or b.

I use the 90 to practice with, helps me focus on fundamentals, getting the ball in the middle of the stringbed and really grooves my serve. Then i pick up my regular sticks and watch the racquet head speed bump up without too much breakdown of technique.

My order of preference, PS 6.1 90>KPS 88>K90>PS 85>Ncode. I don't like how stiff the Ncode feels and the K90 is somewhere in between. The PS 6.1 90 is the easiest Pro Staff to swing and still keeps the feel of the Pro Staff line. The KPS 88 was a sledgehammer but was very difficult to generate racquet speed compared to the PS 6.1 90. If you could generate massive racquet speed, KPS 88 is the racquet for you.

I keep forgetting that these have a much tighter string bed compared to my Babolat Pure Storm Tour GT so if you are coming from another frame that has a rather open string pattern, drop the tension at least a few lbs to reduce the string bed stiffness.